Conventionally, various types of image processing techniques are utilized in the field of factory automation (FA) and the like. Typically, image processing technology is employed to shoot an image of an object to be inspected to obtain image data, and therefrom identify letters, markings and the like provided on the object, inspect whether the object has a damaged surface, register components to be assembled, and the like, and is introduced in various production facilities and the like.
To utilize such image processing technology, it is necessary to appropriately obtain an image shot of the object. Accordingly, image processing systems are often provided with an illumination apparatus to expose the object to light to ensure appropriate illumination intensity in shooting an image of the object. The illumination apparatus is generally equipped with a low power consumption and long life, high brightness light emitting device, such as a light emitting diode (LED), as a light source.
One such illumination apparatus attached to the above described image processing system is referred to as a bar/line type illumination apparatus. The bar/line type illumination apparatus emits light for illumination at a surface having a predetermined width and extending linearly, and has a structure having an elongate substrate populated with light emitting devices aligned in a line or a matrix.
The bar/line type illumination apparatus is assembled in structures, which are disclosed for example in Japanese Patent Laying Open No. 2007-059073 (Patent Literature 1) and WO2010/007835 (Patent Literature 2).
Patent Literature 1 discloses a bar/line type illumination apparatus including a casing having a bottom wall and a pair of sidewalls, a board disposed on the bottom wall and populated with light emitting devices, and a lens array thereon having a plurality of lens portions, and the lens array has an upper surface with an end fitted to an engagement hook of the pair of sidewalls of the casing so that the lens array and the casing sandwich and secure the populated board to provide an assembly structure.
Patent Literature 2 discloses a bar/line type illumination apparatus including a casing having a bottom wall and a pair of sidewalls, a resiliently compressive heat radiation member thereon, a board thereon populated with light emitting devices, and a lens array thereon having a plurality of lens portions, and the lens array has an engagement hook fitted in an engagement recess of the pair of sidewalls of the casing so that the lens array and the casing sandwich and secure the populated board and the heat radiation member to provide an assembly structure.